DESCRIPTION (Adapted from the applicant's description) Increasing clinical evidence suggests that many organ damages in acquired immunodeficiency syndrome (AIDS) patients appear to be related, at least in part, to endothelium dysfunction. However, the mechanisms are unknown. This group hypothesizes that HIV/SIV Env glycoprotein (gp120) may be play a major role in endothelial dysfunction. Specifically, these investigators intend to: 1. Determine the effects of the HIV/SIV gp120 on endothelial structure and functions. Human umbilical core vein endothelial cell (HUVEC) culture (in vitro) model and a novel human saphenous veinperfusion culture (ex vivo) model will be used. Soluble HIV gp120 or virus-like particles (VLPs) will be added to cell and vein culture systems. A novel model of local infusion of SIV VLPs to the carotid arteries of rhesus macaques (in vivo model) will also be developed and used in this study. For structure study, the endothelial morphometry, proliferation, and apoptosis will be quantitatively analyzed. For function study, the endothelial-regulated vessel contraction and relaxation activities will be quantitatively examined. 2. Determine the effects of the HIV/SIV gp120 on the gene expression that controls vessel structure and functions. Two gene expression activities of endothelial cells (nitric oxide [NO] and endothelin-1 [ET-1]) will examined. The NO production, endothelial constitutive NO synthase (ecNOS) activity, and ecNOS expression at both protein and mRNA levels will be quantitatively analyzed. The secretion and expression at both protein and mRNA levels of ET-1 by endothelial cells will be quantitatively examined. 3. Define the molecular mechanisms of HIV gp120-endothelium interaction. These studies will be performed in HUVEC culture and perfusion human vein culture models. For signal transduction studies, intracellular calcium concentration [Ca2+]I, protein kinase C (PKC), and tyrosine kinase (TK) activities will be quantitatively analyzed. For protein interaction studies, specific binding assays will be quantitatively analyzed. The possibility of presence of noval cell membrane proteins on endothelial cells that specifically interact with HIV gp120 will be explored by protein-protein interaction experiments, and protein purification and characterization techniques.